The present invention relates to an apparatus for cutting arbitrary shapes into material, and more particularly to cutting arbitrary shapes in synthetic plastic foam material, such as styrofoam or polystyrene.
Heating resistive wires, such as "constantan," is known in the prior art: passing sufficient current through a resistive wire brings the wire to temperatures in the range from 200.degree. C through 300.degree. C. This heat range has been found to be sufficient to cut synthetic plastic foam material, such as styrofoam. The prior art cutting devices, however, have the disadvantage of having the single capability of cutting straight line patterns. Specifically, the wire of the prior art is extended across two bracket arms while the workpiece is guided towards the extended wire, or, the workpiece may be kept stationary and the wire may be moved relative thereto.
A disadvantage of these cutting devices of the prior art is that they are restricted to cutting linear patterns only. There is no capability for cutting curvilinear or closed line patterns, such as circles or bore holes. In applications such as modelling landscape scenes, it is extremely important to create a true-to-life setting; hence, the single capability of cutting either horizontal or vertical lines severely restricts the various applications to which the synthetic plastic foam material shapes can be utilized.
Furthermore, the prior art does not teach, nor provide, for any readily operable desired interruption of the electrical heating current flow for the sake of the convenience of the operator, or, for the termination of the cutting function. Thus, an unnecessary current drain from a supply source will result. This is especially disadvantageous when batteries are used, since such a supply source has a limited current storage capability.
Furthermore, the electrical switch provides for operator safety. The resistive wires of the prior art are supported by electrically conductive support clamps which are respectively mounted on the wire-positioning elements. If interruption of the electric current flow were desired, the operator has to unclip these clamps. Inasmuch as the clamps were not only uninsulated from the electrical current, but were moreover still hot, the operator found it convenient to omit the step of unclipping the clamps; thus increasing the aforementioned current drain.